Generally speaking, the present invention relates to a gravity/spring assisted electrical current operated relay which comprises: a relay body having a top and bottom portion and a cavity therein, a magnetic coil carried by the body, an electrical contact and armature assembly slideably carried in the cavity and biased such that the armature rests on the bottom portion. The relay includes anti-tracking means disposed in the cavity to prevent electrically conductive paths from arc tracking within the cavity. In addition, there is a recess in the bottom of the cavity to receive unwanted foreign materials to permit the armature to rest on the bottom of the cavity. Guide means are provided in the cavity to prevent binding of the armature and to provide additional space to receive foreign matter. A holder is provided to receive electrical lead wires and terminals.
The present invention is directed to a current-operated relay for use in starting fractional horsepower single phase induction motors particularly in hermetically-sealed compressor motors used in the refrigeration industry.
Starting relays are designed to lift a steel armature by the magnetic pull of a coil. This armature mechanism raises a bar with contacts, to close the starting circuit between mating contacts. The electrical reliability of the contact depends upon the contact force. Such force is maintained by a spring which is compressed by the upward motion of the armature, as it seeks the center of the magnetic field created by the current in the relay coil. The relay armature pulls up at instant of start and closes the start motor winding. It drops out in a half second or so as motor reaches speed and running-winding current drops back.
When relays of this type are used in the refrigeration industry, they must of necessity be made very small and compact. This leads to many problems. For example, because of the miniature size of the relay, it is very difficult to maintain positive contact between the electrical contacts of the relay. In addition, because of the very small cavity within which the component parts of the relay must operate, arcing problems arise causing electrical conducting paths to be built up around the interior of the body. This, of course, causes many spurious arcing problems. Furthermore, because of the very small size of the cavity, particle buildup causes by wear presents a problem in the relationship of the armature to the field coil. In addition, binding of the armature as it moves within the small cavity presents a problem.